Investigation of Mobility Limiting Mechanisms in Undoped Si/SiGe Heterostructures

We perform detailed magnetotransport studies on two-dimensional electron gases (2DEGs) formed in undoped Si/SiGe heterostructures in order to identify the electron mobility limiting mechanisms in this increasingly important materials system. By analyzing data from 26 wafers with different heterostructure growth profiles we observe a strong correlation between the background oxygen concentration in the Si quantum well and the maximum mobility. The highest quality wafer supports a 2DEG with a mobility of 160,000 cm^2/Vs at a density 2.17 x 10^11/cm^2 and exhibits a metal-to-insulator transition at a critical density 0.46 x 10^11/cm^2. We extract a valley splitting of approximately 150 microeV at a magnetic field of 1.8 T. These results provide evidence that undoped Si/SiGe heterostructures are suitable for the fabrication of few-electron quantum dots.Comment: Related papers at http://pettagroup.princeton.ed

The effect of cutting temperature on hole quality when drilling CFRP/metal stack

The carbon fiber reinforced plastic (CFRP) are widely used in stacks with metals. That allows obtaining components with high strength and reduces weight. Holes’ drilling is a basic operation of CFRP/metal and metal/CFRP stacks machining. The most common problems of CFRP/metal stacks drilling are CFRP delamination, fiber pull – out, thermal degradation and low quality of hole surface. In this study the effect of cut ting temperature on the hole quality was provided. It was experimentally established that drilling of CFRP/metal stack was accompanied with a significant change of cutting temperature in the cutting zone during the transition of drill from CFRP to metal plate.Волокнисті полімерні композиційні матеріали (вуглепластики) широко використовуються в пакетах з металами. Це дозволяє отримати компоненти з високою міцністю, разом з тим забезпечивши зниження ваги. Свердління отворів є основною механічною операцією при обробці пакетів вуглепластик / метал і метал / вуглепластика. Найбільш поширені проблеми механічної обробки пакетів вуглепластик / метал є розшарування вуглепластика, витягування волокон, термічна деструкція і низька якість поверхні отвори. У статті представлено дослідження впливу дію температури різання на якість отворів. Експериментально було встановлено, що свердління пакета вуглепластик / сталь супроводжувався істотною зміною температури різання в зоні різання при переході свердла з вуглепластика до металевої пластини

Determining the influence and effects of manufacturing variables on sulfur dioxide cells

A survey of the Li/SO2 manufacturing community was conducted to determine where variability exists in processing. The upper and lower limits of these processing variables might, by themselves or by interacting with other variables, influence safety, performance, and reliability. A number of important variables were identified and a comprehensive design experiment is being proposed to make the proper determinations

Evaluation of the bond performance in FRP-brick components re-bonded after initial delamination

The bond behavior between Fiber Reinforced Polymers (FRPs) and masonry substrates has been the subject of many studies during the last years. Recent accelerated aging tests have shown that bond degradation and FRP delamination are likely to occur in FRP-strengthened masonry components under hygrothermal conditions. While an investigation on the possible methods to improve the durability of these systems is necessary, the applicability of different bond repair methods should also be studied. This paper aims at investigating the debonding mechanisms after repairing delaminated FRP-strengthened masonry components. FRP-strengthened brick specimens, after being delaminated, are repaired with two different adhesives: a conventional epoxy resin and a highly flexible polymer. The latter is used as an innovative adhesive in structural applications. The bond behavior in the repaired specimens is investigated by performing single-lap shear bond tests. Digital image correlation (DIC) is used for deeper investigation of the surface deformation and strains development. The effectiveness of the repair methods is discussed and compared with the strengthened specimens.The first author acknowledges the financial support of the Portuguese Science Foundation (Fundacao de Ciencia e Tecnologia, FCT), through grant SFRH/BPD/92614/2013. Additional acknowledgement goes to Sika Poland for providing the PS polymer to the laboratory of the Minho University in Portugal

Resistance training practices of Brazilian Olympic sprint and jump coaches: toward a deeper understanding of their choices and insights (part III)

In the final part of this three-article collection on the training strategies of Brazilian Olympic sprint and jump coaches, we provide a detailed description of the resistance training methods and exercises most commonly employed by these speed experts. Always with the objective of maximizing the sprint and jump capabilities of their athletes, these experienced coaches primarily utilize variable, eccentric, concentric, machine-based, isometric, complex, and isoinertial resistance training methods in their daily practices. Squats (in their different forms), Olympic weightlifting, ballistics, hip thrusts, lunges, calf raises, core exercises, leg curls, stiff-leg deadlifts, and leg extension are the most commonly prescribed exercises in their training programs, during both the preparatory and competitive periods. Therefore, the current manuscript comprehensively describes and examines these methods, with the additional aim of extrapolating their application to other sports, especially those where sprint speed is a key performance factor

Involvement of the histaminergic system in the resuscitating effect of centrally acting leptin in haemorrhagic shock in rats

Leptin, acting centrally as a neuromodulator, induces the activation of the sympathetic nervous system, which may lead to a pressor action in normotensive animals. In haemorrhagic shock, leptin administered intracerebroventricularly (icv.) evokes the resuscitating effect, with long-lasting rises in mean arterial pressure (MAP) and heart rate (HR), subsequent increase in peripheral blood flows, and a 100% survival at 2 h. Since leptin is able to activate histaminergic neurons, and centrally acting histamine also induces the resuscitating effect with the activation of the sympathetic nervous system, in the present study, we investigated an involvement of the histaminergic system in leptin-evoked cardiovascular effects in haemorrhagic shock. The model of irreversible haemorrhagic shock, with MAP decreased to and stabilised at 20 - 25 mmHg, has been used. Leptin (20 μg) given icv. at 5 min of critical hypotension evoked 181.5% increase in extracellular hypothalamic histamine concentration during the first 10 min after injection. Rises in MAP, HR and renal, mesenteric and hindquarters blood flows induced by leptin were inhibited by icv. pre-treatment with histamine H1 receptor antagonist chlorpheniramine (50 nmol). In contrast, there was no effect of H2, H3 and H4 receptor antagonists ranitidine (25 nmol), VUF 5681 (25 nmol) and JNJ 10191584 (25 nmol), respectively. In conclusion, the histaminergic system is involved in centrally-acting leptin-induced resuscitating effect in haemorrhagic shock in rats

MPI Informatics building model as data for your research

In this report we describe the MPI Informatics building model that provides the data of the Max-Planck-Institut f\"{u}r Informatik (MPII) building. We present our motivation for this work and its relationship to reproducibility of a scientific research. We describe the dataset acquisition and creation including geometry, luminaires, surface reflectances, reference photographs etc. needed to use this model in testing of algorithms. The created dataset can be used in computer graphics and beyond, in particular in global illumination algorithms with focus on realistic and predictive image synthesis. Outside of computer graphics, it can be used as general source of real world geometry with an existing counterpart and hence also suitable for computer vision